Urban mining

by ambiguous architect

The construction industry produces around 40% of global solid waste, yet we stand surrounded by unused materials, the latent building stock of a throwaway world. Let’s return to make (do) and mend. Positive impact design turns that waste into resource, what already exists to be used.

Construction and Demolition Waste (C&D)

Every demolition site is a quarry in disguise. Recycling concrete can become new aggregate; brick dust can replace cement; glass can return as another form. Companies like Rotor Deconstruction (Belgium)  https://rotordc.com/ have shown that architectural intelligence lies in careful disassembly, not demolition. Their reuse of resources are proof that cities can mine themselves known now as urban mining.Each small decision, specifying crushed concrete instead of new gravel, saves carbon, reduces extraction, and writes a new kind of civic poetry: the building as reincarnation.

Agricultural By-Products

Beyond the city, we can find more waste products full of potential. Rice husk ash strengthens low-carbon cement; hemp and flax make breathable, carbon-negative walls; straw and bagasse can become boards and panels.

Projects like IsoHemp in Belgium and Biohm in the UK demonstrate how crop residues can replace high-impact materials. Here, sustainability and social equity converge, farmers become material suppliers, and rural waste becomes urban fabric.

Industrial By-Products Industry, too, is rich in potential. The by-products of energy and mining, fly ash, slag, red mud, and gypsum, can all replace carbon-heavy cement or plaster. Lafarge’s EcoCem and Solidia Technologies are already producing concretes that trap CO₂ rather than emit it. The principle is simple but radical: specify it don’t waste it.

Timber and Biomass Waste

Even renewable materials generate waste, offcuts, sawdust, bark, and dust.Yet from this detritus, new composites and finishes emerge. Woodio (Finland) transforms wood shavings into waterproof basins; Stora Enso reintegrates CLT waste into new panels.By designing for reuse, the architect keeps carbon embodied and craftsmanship visible, a cultural cycle of care rather than consumption.

Specification as an Act of Ethics

The greatest positive impact begins in the smallest design act: the specification note. When an architect chooses a recycled aggregate, a low-carbon binder, or a biobased panel, they rewrite the environmental legacy of their project. Specification is not just paperwork.

Positive impact design demands that we:

• Map the full life cycle of every material before it’s ordered.

• Prioritise local sourcing to reduce transport emissions.

• Plan for disassembly so that today’s wall can be tomorrow’s something.

• Write reusability into contracts so that building becomes temporary stewardship, not ownership.

  
  

A truly beautiful building is one that gives back: to air, to soil, to community, to memory. Its materials are alive with stories of transformation, waste turned to wonder, residue turned to resource.